THE USE OF WOOD ASHES. 183 



importance of manuring with ashes has been long 

 recognised by agriculturists as the result of experi- 

 ence. So great a value, indeed, is attached to this 

 material in the vicinity of Marburg and in the 

 Wetterau,* that it is transported as a manure from 

 the distance of 18 or 24 miles. Its use will be at 

 once perceived, when it is considered that the 

 ashes, after having been washed with water, con- 

 tain silicate of potash exactly in the same propor- 

 tions as in straw (10 Si 03 + K O.), and that their 

 only other constituents are salts of phosphoric acid. 



But ashes obtained from various kinds of trees are 

 of very unequal value for this purpose ; those from 

 oak-wood are the least, and those from beech the 

 most serviceable. The ashes of oak-wood contain 

 only traces of phosphates, those of beech the fifth 

 part of their weight, and those of the pine and fir 

 from 9 to 15 per cent. The ashes of pines from 

 Norway contain an exceedingly small quantity of 

 phosphates, namely, only 1*8 per cent, of phosphoric 

 acid. (Berthier.) 



With every 100 Ibs. of the lixiviated ashes of 

 the beech which we spread over a soil, we furnish 

 as much phosphates as 460 Ibs. of fresh human" ex- 

 crements could yield. Again, according to the analy- 

 sis of De Samsure, \ 00 parts of the ashes of the 

 grain of wheat contain 32 parts of soluble, and 4 4 '5 

 of insoluble phosphates, in all 76*5 parts. Now the 



* Two well-known agricultural districts ; the first in Hesse-Cassel, 

 the second in Hesse-Darmstadt. TBANS. 



